Electrical Junction Box

This application is the U.S. national stage of PCT/JP2023/018476 filed on May 17, 2023, which claims priority of Japanese Patent Application No. JP 2022-089777 filed on Jun. 1, 2022, the contents of which are incorporated herein.

The present disclosure relates to an electrical junction box that includes a board.

Heretofore, an electrical junction box that accommodates electronic components such as fuses and relays is mounted in vehicles.

The electrical junction box includes a housing, and the housing is constituted by a first case that is open on one surface side thereof and accommodates the electronic components, and a second case that covers the one surface side of the first case that is open, for example (see JP 2016-208561A).

As the number of electronic components that need to be accommodated increases due to diversification of functions in vehicles, the sizes of electrical junction boxes have also increased. However, as the number of electronic components increases and the sizes of electrical junction boxes increase, the electrical junction boxes have become likely to be affected by heat generated in electronic components when energized. That is to say, there has been a problem in that warping occurs in an end portion in the lengthwise direction of the electrical junction box due to a difference in amount of thermal expansion (amount of contraction) caused by heat generated in electronic components.

However, with the electrical junction box in JP 2016-208561A, in which such a problem is not taken into consideration, the problem cannot be addressed.

In view of this, an object of the present disclosure is to provide an electrical junction box that can suppress the occurrence of warping due to heat generated in electronic components.

An electrical junction box according to an embodiment of the present disclosure is an electrical junction box that includes: a first wall that comes into contact with a mount target, and a second wall that includes a surface that opposes the first wall and an inner rib that protrudes from the surface, and an outer rib protrudes from an opposite surface that is opposite to the opposing surface of the second wall.

According to the present disclosure, it is possible to provide an electrical junction box that can suppress the occurrence of warping due to heat generated in electronic components.

First, embodiments of the present disclosure will be listed and described. In addition, at least some of the embodiments described below may be combined as appropriate.

An electrical junction box according to an embodiment of the present disclosure is an electrical junction box that includes: a first wall that comes into contact with a mount target, and a second wall that includes a surface that opposes the first wall and an inner rib that protrudes from the surface, and an outer rib protrudes from an opposite surface that is opposite to the opposing surface of the second wall.

According to such an embodiment, an inner rib is provided on the opposing surface of the second wall, and an outer rib is provided on the opposite surface that is opposite to the opposing surface. Therefore, a difference in contraction that has occurred between the second wall and the inner rib caused by a difference in amount of heat generated during an operation remains is offset by a difference in contraction that has occurred between the second wall and the outer rib, and it is possible to suppress the occurrence of warping of the second wall.

In the electrical junction box according to the embodiment of the present disclosure, the inner rib and the outer rib each have a shape of a plate, and a thickness of the second wall is larger than thicknesses of the inner rib and the outer rib.

According to such an embodiment, the thickness of the second wall is larger than the thicknesses of the inner rib and the outer rib, and thus, heat that has generated during an operation is likely to remain in the second wall more than the inner rib and the outer rib, and a difference in amount of heat that remains in this manner causes a difference in contraction that is a cause of warping. However, a difference in contraction that has occurred between the second wall and the inner rib is offset by a difference in contraction that has occurred between the second wall and the outer rib, thus suppressing the occurrence of warping of the second wall.

In the electrical junction box according to the embodiment of the present disclosure, an end portion in a lengthwise direction of the second wall is inclined so as to approach the first wall toward a leading end of the second wall, a plurality of the outer ribs are provided, and lengths of the outer ribs in an opposing direction of the first wall and the second wall increase toward a leading end in the lengthwise direction of the second wall.

According to such an embodiment, the end portion of the second wall is inclined so as to approach the first wall toward the leading end thereof, and the lengths of the outer ribs in the opposing direction of the first wall and the second wall increase toward the leading end in the lengthwise direction thereof. Therefore, a difference in contraction that has occurred between the second wall and the inner rib and a difference in contraction that has occurred between the second wall and the outer ribs are set to the same degree and are offset, thereby suppressing the occurrence of warping of the second wall.

In the electrical junction box according to the embodiment of the present disclosure, the outer ribs are provided in an end portion in the lengthwise direction of the second wall.

According to such an embodiment, the outer ribs are provided in the end portion of the second wall in which significant warping occurs. Therefore, it is possible to more efficiently suppress the occurrence of warping of the second wall.

In the electrical junction box according to the embodiment of the present disclosure, a side wall extending in the opposing direction is disposed around an edge of the second wall, and a distance between the first wall and a leading end of the side wall in the opposing direction is fixed.

According to such an embodiment, the distance between the first wall and the leading end of the side wall in the opposing direction is fixed. Thus, it is possible to prevent a local decrease in the strength of the end portion of the second wall due to the end portion of the second wall being inclined so as to approach the first wall.

An electrical junction box according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to illustrations of these, but is indicated by the claims, and is intended to include all modifications that are within the meanings and the scope that are equivalent to those of the claims.

is a perspective view of an electrical junction boxaccording to an embodiment of the present disclosure,are a plan view and a side view of the electrical junction boxaccording to the embodiment, andis an exploded view of the electrical junction boxaccording to the embodiment.is a plan view of the electrical junction box, andis a side view of the electrical junction box.

The electrical junction boxis attached to the outer side of a mount target such as a battery pack(see) of an EV (Electric Vehicle), for example. For convenience of description,shows a state where the electrical junction boxis attached to the battery pack.

The electrical junction boxincludes a housingthat accommodates a fuse, a board, and the like. The housingis a flattened housing, is substantially rectangular in plan view, and has a shape in which one corner of one end portion in the lengthwise direction is notched in a stepped manner. The housingis made of a resin, for example, and is constituted by a lower casethat is attached to the mount target, and an upper casethat covers the lower case. For convenience of description, the following description is given in which the upper caseside is the upper side, and the lower caseside is the lower side.

The lower casehas a shape of a box in which one surface on the upper caseside is open. The lower caseincludes a bottom wall(first wall) whose outer side surface comes into contact with the mount target, and a side wallextending perpendicularly from an edge of the bottom wallto the upper caseside. Ribs are formed at a plurality of locations inside the lower case(see).

Recessed portionsare formed in the two end portions in the lengthwise direction of the bottom wallof the lower case, and a recessed portionis formed in an intermediate portion. The recessed portionand the recessed portionsare formed at positions corresponding to fastening portions(mount portions) of the upper case, which will be described later.

Specifically, the recessed portionsare respectively formed in the two corners of each of the two end portions of the lower case. The recessed portionsare substantially rectangular in plan view, the side wallis bent at substantially the right angle in the recessed portionsand the corners of each recess are chamfered (see).

In addition, the recessed portionis formed in an intermediate portion on a longer edge side of the lower case. The recessed portionis substantially rectangular in plan view. In the recessed portionthe side wallis recessed inward in the lower case, and the corners of the recess are chamfered (see).

The upper casehas a shape of a box in which the one surface on the lower caseside is open. The lengths of the upper casein the lengthwise direction and in the width direction orthogonal to the lengthwise direction are slightly larger than those of the lower case, and the upper casecovers the lower case.

In addition, the upper caseincludes a ceiling wall(second wall) that opposes the bottom wallof the lower case, and a side wallthat is disposed around an edge of the ceiling walland extends in the up-down direction. The fastening portionsfor attaching the upper case(the housing) to the mount target are provided in the two end portions and an intermediate portion in the lengthwise direction of the upper case.

Specifically, the fastening portionsare respectively provided at the two

corners of one end portion in the lengthwise direction of the upper case, and are respectively provided at the two corners of the other end portion and between the two corners. Furthermore, also in the intermediate portion in the lengthwise direction of the upper case, three fastening portions, namely the fastening portionsare aligned in the width direction. The fastening portionsprotrude from the inner surface(opposing surface) of the ceiling wallthat opposes the bottom wall(see), and the fastening portionsother than the one fastening portionin the substantially central portion of the ceiling wallare provided in the vicinity of the side wall(see).

A plurality of inner ribsprotrude from the inner surfaceof the ceiling wall(see). The plurality of inner ribsare aligned in the lengthwise direction, and the inner ribseach has a shape of a plate extending in the width direction. In addition, the thickness of each inner ribis smaller than the thickness of the ceiling wall.

The fastening portionshave a bottomed tubular shape, and are open on the ceiling wallside. In addition, fixing through holesthat are used when attaching the housingto the mount target are formed in the bottoms of the fastening portions(see). The housing(the electrical junction box) can be attached to the mount target by inserting screws into the fixing through holesof the fastening portionsfrom the mount target and threading the screws into nuts (not illustrated) provided in the fastening portions.

As described above, inside the recessed portionand the recessed portionsof the lower case, the fastening portionsof the upper caseare respectively disposed.

Various connection portionsfor connection to another apparatus are provided at a plurality of locations of an outer surface(opposite surface) on the opposite side to the inner surfaceof the ceiling wall. In addition, a plurality of mount seatsfor relaysare provided in a substantially central portion of the outer surfaceof the ceiling wall, and a plurality of relaysare mounted thereto. For convenience,does not illustrate the relays.

Moreover, a plurality of outer ribsprotrude from the outer surfaceof the ceiling wall. The outer ribsinclude first outer ribsfor preventing warping caused by gravity and second outer ribs(outer ribs) for preventing warping caused by a difference in thermal expansion as will be described later.

The first outer ribshave a shape of a triangular plate, and are provided mainly in peripheral edge portions of the ceiling wall. That is to say, the length in the up-down direction of each of the first outer ribsdecreases toward the peripheral edge from a central portion of the ceiling wall. As described above, the first outer ribssuppress the occurrence of warping of the ceiling walldue to the weight of the relays(see) mounted in the central portion.

The second outer ribshave a shape of a plate, and are provided in an end portion in the lengthwise direction of the ceiling wall. For convenience, in the present embodiment, a case will be described in which, as an example, the second outer ribsare provided only in one end portion of the ceiling wall, but there is no limitation thereto, and the second outer ribsmay be provided in two end portions. The thickness of each second outer ribis smaller than the thickness of the ceiling wall.

is a partial perspective view showing the second outer ribsprovided in one end portionof the ceiling wallin the electrical junction boxaccording to the embodiment, andis a longitudinal cross-sectional view taken along the line V-V in.

As described above, the second outer ribsare provided in the one end portionof the ceiling wall. The second outer ribsare provided at positions corresponding to the inner ribsin the up-down direction, or in the vicinities of the corresponding positions. The lengths (hereinafter, also referred to as a “height”) in the up-down direction of the second outer ribsincrease toward the peripheral edge of the ceiling wall.

As shown in, the one end portionin the lengthwise direction of the ceiling wallis inclined downward. That is to say, the one end portionof the ceiling wallin which the second outer ribsare provided is inclined so as to approach the bottom wallof the lower casetoward the peripheral edge thereof, and the distance between a portion of the ceiling wallother than the one end portionand the bottom wallis kept fixed. In addition, distances L between the bottom walland the upper ends of all of the second outer ribs(hereinafter, referred to as “upper end distances L”) are substantially the same.

As described above, while the upper end distances L for the plurality of second outer ribsare the same, the one end portionof the ceiling wallis inclined downward toward the peripheral edge thereof, and thus the length in the up-down direction of each of the second outer ribsincreases toward the peripheral edge of the ceiling wall.

In addition, as described above, the one end portionof the ceiling wallis inclined downward toward the peripheral edge thereof, but, in the up-down direction, the distance between the bottom wallof the lower caseand the leading end of the side wallof the upper case, that is to say the upper end of the side wallis fixed.

That is to say, as shown in, a distance Hbetween the bottom walland the upper end of the side wallalong the peripheral edge of the one end portionof the ceiling wallin the lengthwise direction, that is to say along a shorter edge of the ceiling wallis the same as a distance Hbetween the bottom walland the upper end of the side wallalong a longer edge of the ceiling wall.

Since the electrical junction boxaccording to the embodiment has such a configuration, as described above, the second outer ribscan suppress the occurrence of warping of the ceiling wallcaused by a difference in thermal expansion. Detailed description will be given below.

is a partial cross-sectional view schematically showing the one end portionof the ceiling wallin which the second outer ribsare provided, in the electrical junction boxaccording to embodiment, andis a diagram showing a result of simulating warping of the electrical junction boxcaused by a difference in thermal expansion.. For convenience,shows only contours of the electrical junction box. In addition,shows a case where the one end portionof the ceiling wallis not inclined, and the second outer ribsare not provided, andshows a case where the one end portionof the ceiling wallis inclined, and the second outer ribsare provided, that is to say a case of the electrical junction boxaccording to the present embodiment.

In a case where the one end portionof the ceiling wallis not inclined, and only the inner ribsand the first outer ribsare provided (see the one-dot chain line in), a problem occurs in that an end portion of the ceiling wallis warped to the upper side where the inner ribsare not provided, due to heat generated in the relayor the like while the electrical junction boxis in operation (see).

It is assumed that the cause for this is that, since the ceiling wallis thicker than the inner ribs, and is in direct contact with a heat source (for example, the relay) and the like, the ceiling wallretains a large amount of generated heat, while the inner ribsare thinner and are likely to be air-cooled, and thus a contraction (thermal expansion) difference occurs between the ceiling walland the inner ribs.

In contrast, in the electrical junction boxaccording to the present embodiment, as described above, the second outer ribsare formed on the outer surfaceof the ceiling wall. Thus, a difference in contraction that has occurred between the ceiling walland the inner ribsis offset by a difference in contraction that has occurred between the ceiling walland the second outer ribsand it is possible to suppress the occurrence of warping of the ceiling wall.